Image sensors have become ubiquitous. They are widely used in digital still cameras, cellular phones, security cameras, as well as, medical, automobile, and other applications. The technology used to manufacture image sensors, and in particular, complementary metal-oxide-semiconductor (“CMOS”) image sensors, has continued to advance at great pace. For example, the demands of higher resolution and lower power consumption have encouraged the further miniaturization and integration of these image sensors.
Conventional CMOS image sensors typically have a configuration in which a plurality of pixels are arranged into a two-dimensional array, where each pixel includes a photodiode and associated pixel transistors. Recently, with the continued miniaturization of image sensors, in order to reduce the area occupied by each pixel, a pixel sharing structure has been implemented where pixel transistors are shared among several photodiodes. However, typical layouts of a pixel sharing structure often suffer from leakage problems between various portions of the pixel transistors due to their close proximity to one another.